Question

eutrophication is often the result of ________. a. increases in animal populations b. lack of oxygen in the water c. fertilizer runoff entering aquatic ecosystems d. a decrease in phytoplankton populations please select the best answer from the choices provided

Explanation:

Eutrophication occurs when excessive nutrients, often from fertilizer runoff, enter aquatic ecosystems. This leads to over - growth of algae and other plants. Animal population increases are not the main cause. Lack of oxygen is a consequence, not a cause. A decrease in phytoplankton populations is not the cause of eutrophication. Fertilizer runoff provides nutrients like nitrogen and phosphorus which fuel eutrophication.

Answer:

C. fertilizer runoff entering aquatic ecosystems